1. Field of the Invention
The present invention relates generally to expansion bolts. Particularly, the present invention relates to expansion bolts used with “manway” covers for access to enclosed spaces such as tanks, conduits, storage areas, heat exchanger tubes. More particularly, the present invention relates to expansion bolts used with mechanisms to assist in the removal of “manway” covers. Even more particularly, the present invention relates to expansion bolts used with mechanisms for handling the removal and installation of “manway” covers that are either too hazardous, or too heavy, or too cumbersome to be handled by an unaided individual.
2. Description of the Prior Art
Manway covers are typically large, heavy, metal plates that are bolted to an opening. For purposes of the present invention, the definition of “manway covers” expressly means any heavy covers or closures used on pressure vessels, vacuum vessels, atmospheric vessels, heat exchangers, heat exchanger channel covers, heat exchanger channels, heat exchanger bonnets, or any type of blanking plate and is not construed to be limited to only covers used on openings that are dimensionally-sized to allow passage of a human. The most common are circularly-shaped and mate to a flange by way of a plurality of bolts evenly spaced around the periphery of the opening. However, it should be understood that the heavy covers may be any shape. The defined manway covers typically provide access to enclosed spaces such as tanks, conduits, storage areas, transfer tubes, pressure vessels, vacuum vessels, atmospheric vessels, heat exchangers, heat exchanger channel covers, heat exchanger channels, heat exchanger bonnets, and the like.
Routine servicing and inspection requirements as well as other operating conditions necessitate periodic removal of these manway covers. In view of the typical location and weight of the manway covers, it is not a simple task to remove the cover or to re-install the same. Removal is currently accomplished with the use of hand operated davit swing arms, chain falls, ratchet hoists, hinge devices, and brute force. Except for davit swing arms and hinge devices, it is necessary during the removal process to lower the covers a distance to a level surface.
Various devices have been devised to facilitate manway cover removal and re-installation. U.S. Patent Application Publication 2008/0256753 (2008, DePietro et al.) discloses a portable manway cover hinge device. The hinge device has a pair of hinge plates where each hinge plate has a support member with a hinge aperture positioned for alignment with a bolt opening of a manway cover and a manway flange, a linkage member adjacent a first end of each hinge plate and extending out of the plane of the hinge plate, and a pivotal connection coupling overlapping pairs of the linkage member of the pair of hinge plates.
U.S. Patent Application Publication 2008/0256866 (2008, DePietro et al.) discloses a portable manway cover hinge device. The hinge device has a pair of elongated hinge members where each hinge member has a pair of longitudinally-aligned, elongated apertures, a support member slidably connected to each of the elongated apertures where the support member has a pin receiving end, and a linkage member pivotally connected to each of the pair of elongated hinge members.
U.S. Patent Application Publication 2005/0242051 (2005, Porebski et al.) discloses a removable cover support system having a base member and a securing mechanism slidably insertable through at least one of a cover flange hole of a cover assembly, a retaining sleeve connected to the securing base assembly, a swingarm assembly rotatably supported by the retaining sleeve, and a lifting mechanism connected to the swingarm assembly.
U.S. Pat. No. 4,519,519 (1985, Meuschke et al.) discloses a davit assembly that is connected with a transfer tube and a hatch cover to move the cover away. The davit assembly, which is a swingarm, is permanently attached to the outside of the transfer tube.
U.S. Pat. No. 4,297,072 (1981, Shah et al.) discloses a manway handling apparatus having a support arm pivotally mountable on equipment having elliptical manway access openings. The support arm when mounted is swingable toward and away from an access opening and carries a bearing block supporting bracket which is longitudinally adjustably positionable on the arm. The bearing block is vertically adjustably positionable in the bracket and slidably supports a shaft which is attachable to an elliptical cover. The shaft carries structure means which when actuated by turning of a crank handle is effective for tilting the cover and to facilitate its installation and removal.
U.S. Pat. No. 4,865,513 (1989, Norris) discloses a portable manway cover handling apparatus. A boom is mounted within a sleeve for longitudinal translation and the sleeve is hinged to a base plate that is securable by a C-clamp to a superstructure beam in front of a manway cover. A hydraulic actuator bears against the sleeve to adjust its elevation. A powered cable winch is joined to one end of the boom and its cable passes through the boom, which is hollow to the opposite end, and about a pulley to a fastener for attachment to an eye secured in the upper edge of the manway cover. A presser foot is hydraulically actuated to bear against the manway cover with the cable attached to the cover so that the bolts holding the cover in place can be removed. Guide pins are provided for installation in the mounting flange to pilot the cover into registration with the bolt holes when the cover is to be mounted rather than demounted.
Some of the prior art devices discuss the use of tapered pins, pins or expansion plugs, however, they suffer from serious disadvantages. These include the fact that the manway covers are extremely heavy and tapered pins, straight pins or expansion plugs would not safely support the weight of the cover or securely hold a cover to the various manway cover swingarm devices or hinge devices causing a serious hazard to a user.
The mechanical attachment of two components with one component having a blind hole and the other component having a through hole has not been feasible without additional machining. The standard practice is to tap the blind hole with threads. A bolt is installed into the tapped hole, which creates a pull-up force to secure the two components with both friction and tensile forces.
Design clearances between bolt diameters and bolt holes allow for lateral movement within the design clearances. Lateral movement between the two components can occur if the interface friction is less than the lateral force between the two components. Locating pins may be installed to precisely locate the two components, but require accurate machining and dowel pins to eliminate lateral movement.
In another application, the two components to be attached both having through holes. It is often desirable to attach these types of components such that the attaching device does not extend beyond or outside one of the through holes. It is also possible to tap one or both of the through holes for receiving a bolt.
However, rules regarding the machining of hardware after certification of certain types of equipment may prevent machining of components without recertification. Recertification of installed equipment operating in the field can be expensive, time consuming, and in many cases impossible.
Therefore, what is needed is a removable expansion device that can safely support the weight of a manway cover as well as hold a manway cover to a manway swingarm device or a manway hinge device without the need to alter the structural integrity of the manway cover or a mating flange.